1. Field of the Invention
Embodiments herein present a method for a feed forward silicide control scheme based on spacer height controlling pre-clean time.
2. Description of the Related Art
Conductive materials, such as silicide, are often formed on the surfaces of semiconductors in order to reduce electrical resistance. A conventional semiconductor, such as a complementary metal oxide silicon (CMOS) device, typically comprises field effect transistors (FETs). Moreover, each FET has a gate stack, which may be offset by one or more spacers. As more fully described below, spacers are conventionally used to protect the sidewalls of a gate stack during the processes required to form silicide on a top surface of the gate stack and within the source/drain region of a transistor.
Prior to the formation of silicide, the CMOS device undergoes a conventional pre-clean process to prepare the top surface of the gate stack and the source/drain region for silicide formation. Unfortunately, the spacers are typically not resistant enough to withstand the pre-clean process, and portions of the spacer may become inadvertently removed. As a result, portions of the gate stack sidewall become exposed. The exposed portions of the gate stack sidewall are then susceptible to silicide formation.
Silicide formed on the sidewalls of the gate stack can lead to electrical shorts between the silicide on the top of the gate stack and the silicide within the source/drain region at the base of the gate stack. As semiconductor devices are continually being scaled down, and the distance between the top of the gate stack and the source/drain region is being reduced, the likelihood of electrical shorts due to the silicide formed on the sidewalls of the gate stack increases.
Furthermore, the pre-clean process can shift the gate stack, damage the screen oxide, and lead to PC to silicon leakage, all of which degrades yield. Thus, a solution is required to avoid the aforementioned disadvantages while increasing performance and yield of the semiconductor with no added cost.